Winding glass ribbon by tensioning interleaving material

ABSTRACT

A method of winding a glass ribbon ( 10 ), including: winding an interleaving material ( 20 ) and the glass ribbon together to produce a roll ( 40 ); and tensioning the interleaving material so as to control a roll inter-layer pressure. By controlling the roll inter-layer pressure, the roll can be formed with straight side walls. The tension in the interleaving material can be controlled so as to be greater than 0 and ≦0.25 pounds per linear inch of width of interleaving material. Also, there is provided an apparatus for winding glass ribbon together with interleaving material into a roll. The apparatus includes: an interleaving material supply path; a glass ribbon supply path; a roll winding mechanism ( 46 ); and a means ( 26 ) for applying tension to interleaving material traveling along the interleaving material supply path, as the interleaving material is wound into roll ( 40 ), so as to produce a pressure between the layers of the roll.

BACKGROUND

This application claims the benefit of priority of U.S. ProvisionalApplication Ser. No. 61/417,908 filed on Nov. 30, 2010 the content ofwhich is relied upon and incorporated herein by reference in itsentirety.

FIELD

The invention is directed to methods and apparatuses for winding glassribbon. More particularly, the invention is directed to methods andapparatuses for winding glass ribbon together with an interleavingmaterial to form a roll.

TECHNICAL BACKGROUND

Although formed as a continuous ribbon, glass is typically segmentedinto sheets as soon as it has cooled and solidified. Recent producttrends—in ePaper front plane substrates, protective cover sheets inphotovoltaic modules, touch sensors, solid state lighting, andelectronics, for example—have resulted in requirements for thinner andthinner glass. As glass thicknesses continue to decrease, however, thesesheets become more flexible. This creates a challenge from a handlingperspective, particularly for glass of 0.3 mm or thinner. Accordingly,there have been attempts to wind thin glass into a roll as a manner offacilitating handling. However, there are several unique features ofglass that create challenges for successfully implementing a windingprocess.

First the edge “beads” of the glass, as formed, are substantiallythicker than the constant thickness area in between. Second, glass isextremely sensitive to surface defects. These defects create stresspoints that generate cracks and lead to breakage. Thus it is notadvisable to have direct surface to surface contact of glass to itself,as is typical in a spooled roll of material. The challenges from thesefirst two characteristics have been addressed by using various interleafmaterials between layers of the glass ribbon when winding.

Third, as noticed by the inventors of the subject matter in the presentdisclosure, and which has gone unaddressed—in terms of effect on windingthin glass ribbon, i.e. 0.3 mm or thinner—is that the forming processcan introduce differential thickness across the width of the glassribbon and/or camber (continuous curvature in one direction caused bydifferential cooling between the two edge beads). When winding a glassribbon with differential cross-ribbon thickness and/or camber, lateralforces are generated in the wound roll that result in angled, ratherthan straight, side walls on the wound roll. In some cases, the angle ofthe side wall may lead to the glass ribbon contacting a flange of aspool onto which the glass ribbon is being wound, thereby risking damageto the glass ribbon. Additionally, the angled side wall of the rollleads to difficulties in processing, when unwinding the roll to use theglass ribbon in a continuous manufacturing process. Accordingly, thereis a need for methods of, and apparatuses for, winding glass ribbontogether with interleaving material so that the roll has straighter sidewalls.

SUMMARY

In order to form a roll of wound glass ribbon having straight sidewalls, the inventors have found that the effects of the differentialcross-ribbon thickness and/or camber, among other things, can becounteracted by appropriately choosing winding conditions. Somepertinent winding conditions are web tension as the roll is formed, andpressure between the layers in the roll, as well as how the tension isapplied during winding of interleaving material and glass ribbon to formthe roll.

More specifically, the inventors found that typical web winding processparameters of 1-2 pounds per linear inch of web tension, and 15-50pounds per square inch of pressure between the layers, when used with athin glass ribbon and interleaving material produced angled side wallsin the roll. Further, contrary to conventional wisdom (which dictatesusing high tensions and inter-layer pressures to achieve betterhandling, better storage, and better density of rolled product), theinventors found that increasing the web tension and pressure between thelayers of glass ribbon and interleaving material actually made the sidewall characteristics worse. Surprisingly, the inventors found that usinglower web tension and lower pressure between the layers producedstraighter side walls in the roll. More particularly, a web tension ofgreater than 0 pounds per linear inch, but 0.25 pounds per linear inchor less (0.3 kg/cm or less), and a pressure between the layers in theroll of 10 pounds per square inch or less (0.07 MPa or less), butgreater than 0 pounds per square inch, produced straight side walls onthe rolled thin glass. In another embodiment, pressure between thelayers in the roll of 7 pounds per square inch or less (0.05 MPa orless), but greater than 0 pounds per square inch, also produced straightside walls on the roll. Furthermore, it is desirable for the pressurebetween the layers in the roll to remain substantially uniform throughthe roll.

Additionally, the inventors found that how the tension is applied duringwinding of interleaving material and glass ribbon has an effect on thestraightness of the sidewalls in the resulting roll. More specifically,tension should be applied to the interleaving material and not to theglass ribbon. That is, little if any tension should be applied to theglass ribbon. More specifically, the only tension applied to the glassribbon should be that from the weight of the ribbon itself in afree-loop used to separate the upstream and rolling processes. If anysignificant tension (i.e., other than from frictional drag within therollers forming the free loop, and other than the weight of the ribbonitself in the free loop) is applied to the glass ribbon itself, theeffects of camber and/or thickness variation are magnified leading toundesirably angled, dished, and/or telescoped, sidewalls in theresulting roll. The tension applied to the interleaving material, asnoted above, should be ≦0.25 pounds per linear inch (of width) (≦0.3kg/cm). Further, the tension should be decreased as a function ofincreasing roll diameter (i.e., the roll including glass ribbon andinterleaving material) and/or of decreasing diameter of theinterleaving-material-supply roll. If the tension is not decreased as afunction of roll diameter, the pressure between the layers in the rollwill increase, gradually applying more and more pressure. If too muchpressure is developed, the roll side-wall characteristics deteriorate.

Also, the type of interleaving material itself may advantageously bechosen to reduce the effects of thickness variation in the glass ribbon.More specifically, if the interleaving material is thickness compliant,or has some give to it when compressed, it can absorb thicknessdifferences that may be present in the glass ribbon. A suitablestiffness for the interleaving material was found to be less than orequal to about 28.14 N/mm, or less than or equal to about 27.12 N/mm, orless than or equal to about 26.1 N/mm, wherein the lower bound for allranges was greater than zero. In order to achieve the above-notedstiffness, the interleaving material may be formed from, for example, apolyethylene foam (either open or closed cell), a corrugated papermaterial, or a sheet of soft polyvinyl material having an embossed ortextured surface.

Also, there is disclosed an apparatus for winding glass ribbon togetherwith interleaving material into a roll. The apparatus includes aninterleaving material supply path, a glass ribbon supply path, a rollwinding mechanism, and a means for applying tension to interleavingmaterial traveling along the interleaving material supply path, as theinterleaving material is wound into the roll, so as to produce pressurebetween the layers of the roll. By applying a suitable tension to theinterleaving material, there is developed a suitable pressure betweenthe layers of glass ribbon and interleaving material in the roll wherebya roll with straight sidewalls can be produced. The means for applyingtension may be a pneumatic brake, a mechanical friction brake, amagnetic particle brake, an electric brake, or a servo motor, forexample. Additionally, the means for applying tension may be coupled toa roll that supplies the interleaving material, or to the interleavingmaterial as it travels along its supply path, either directly or througha roller or roller system. A suitable controller may be coupled to themeans for applying tension so as to control the means for applyingtension in accordance with input received from sensors measuring eitherone or both of the amount of interleaving material on theinterleaving-material-supply roll or the amount of material wound intothe roll of glass ribbon and interleaving material.

Additional features and advantages will be set forth in the detaileddescription which follows, and in part will be readily apparent to thoseskilled in the art from the description or recognized by practicing theinvention as exemplified in the written description and the appendeddrawings. It is to be understood that both the foregoing generaldescription and the following detailed description are merely exemplaryof the invention, and are intended to provide an overview or frameworkto understanding the nature and character of the invention as it isclaimed.

The accompanying drawings are included to provide a furtherunderstanding of principles of the invention, and are incorporated inand constitute a part of this specification. The drawings illustrate oneor more embodiment(s), and together with the description serve toexplain, by way of example, principles and operation of the invention.It is to be understood that various features of the invention disclosedin this specification and in the drawings can be used in any and allcombinations. By way of non-limiting example the various features of theinvention may be combined with one another as the following aspects:

According to a first aspect, there is provided a method of winding aglass ribbon, comprising:

-   -   winding an interleaving material and a glass ribbon together to        produce a roll; and    -   tensioning the interleaving material so as to control a roll        inter-layer pressure as the interleaving material and ribbon are        wound.

According to a second aspect, there is provided a method of winding aglass ribbon, comprising:

-   -   winding an interleaving material and a glass ribbon together to        produce a roll having a substantially constant inter-layer roll        pressure.

According to a third aspect, there is provided the method of aspect 2,wherein the roll inter-layer pressure is controlled by tensioning theinterleaving material.

According to a fourth aspect, there is provided the method of any one ofaspects 1-3, wherein the winding further comprises winding theinterleaving material onto a core for at least one wrap to form a nip ofinterleaving material, and inserting the glass ribbon into the nip.

According to a fifth aspect, there is provided the method of aspect 1 oraspect 3, wherein the tensioning is controlled so as to decrease tensionas a function of increasing roll diameter.

According to a sixth aspect, there is provided the method of aspect 1 oraspect 3, further comprising unwinding the interleaving material from aninterleaving roll, and wherein the tension is controlled so as todecrease as a function of decreasing interleaving-roll diameter.

According to a seventh aspect, there is provided the method of aspect 6,further comprising measuring the diameter of the interleaving roll.

According to an eighth aspect, there is provided the method of any oneof aspects 1, 5, or 6, wherein the tensioning is controlled so as toproduce an approximately constant roll inter-layer pressure between theinterleaving material and the glass ribbon.

According to a ninth aspect, there is provided the method of aspect 2 oraspect 8, wherein the roll inter-layer pressure is ≦10 pounds per squareinch (≦0.07 MPa), and is greater than 0 pounds per square inch.

According to a tenth aspect, there is provided the method of aspect 2 oraspect 8, wherein the roll inter-layer pressure is ≦7 pounds per squareinch (≦0.05 MPa), and is greater than 0 pounds per square inch.

According to an eleventh aspect, there is provided the method of any oneof aspects 1-10, wherein the glass ribbon is ≦0.3 mm thick.

According to a twelfth aspect, there is provided the method of any oneof aspects 1-11, wherein the interleaving material is athickness-compliant material.

According to a thirteenth aspect, there is provided the method of aspect12, wherein the interleaving material is a polyethylene foam sheethaving a stiffness of ≦28.14 N/mm.

According to a fourteenth aspect, there is provided the method of anyone of aspects 1-13, wherein the glass ribbon forms a free loop prior tobeing wound together with the interleaving material.

According to a fifteenth aspect, there is provided the method of aspect14, wherein the only tension pulling against the glass ribbon as it iswound together with the interleaving material is that produced by thefree loop.

According to a sixteenth aspect, there is provided the method of any oneof aspects 1-15, wherein the tension is applied to the interleavingmaterial by a pneumatic break or servo motor coupled to the interleavingmaterial.

According to a seventeenth aspect, there is provided the method of anyone of aspects 1-16, wherein the tensioning is performed so as toproduce a tension of ≦0.25 pounds per linear inch (≦0.3 kg/cm) in theinterleaving material as it is wound into the roll.

According to an eighteenth aspect, there is provided a method ofmanufacturing a glass article, comprising:

-   -   forming a glass ribbon; and    -   winding the glass ribbon according to any one of aspects 1-17.

According to a nineteenth aspect, there is provided the method of aspect18, wherein the glass ribbon is formed by a down-draw process.

According to a twentieth aspect, there is provided an apparatus forwinding glass ribbon together with interleaving material into a roll,comprising:

-   -   an interleaving material supply path;    -   a glass ribbon supply path;    -   a roll winding mechanism; and    -   a means for applying tension to interleaving material traveling        along the interleaving material supply path, as the interleaving        material is wound into the roll, so as to produce a pressure        between the layers of the roll.

According to a twenty first aspect, there is provided the apparatusaccording to aspect 20, wherein the means for applying tension is one ofa pneumatic break and a servo motor coupled to the interleavingmaterial.

According to a twenty second aspect, there is provided the apparatusaccording to aspect 20 or aspect 21, further comprising a measurementdevice positioned to measure the diameter of the roll.

According to a twenty third aspect, there is provided the apparatusaccording to aspect 22, further comprising a controller coupled to themeasurement device and the means for applying tension, wherein thecontroller controls the means for applying tension so as to decrease thetension applied to the interleaving material as a function of increasingroll diameter.

According to a twenty fourth aspect, there is provided the apparatusaccording to any one of aspects 20-23, further comprising a measurementdevice positioned to measure a diameter of a roll from which theinterleaving material is supplied along the interleaving material supplypath.

According to a twenty fifth aspect, there is provided the apparatusaccording to aspect 24, further comprising a controller coupled to themeasurement device and the means for applying tension, wherein thecontroller controls the means for applying tension so as to decrease thetension applied to the interleaving material as a function of decreasinginterleaving-roll diameter.

According to a twenty sixth aspect, there is provided the apparatusaccording to any one of aspects 20-25, wherein the means for applyingtension applies an amount of tension of greater than zero and ≦0.25pounds per linear inch (≦0.3 kg/cm).

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic side view of an apparatus for winding a glassribbon together with interleaving material into a roll.

FIG. 2 is a cross section of a roll, as taken along line 2-2 of FIG. 1.

FIG. 3 is a top view of the apparatus shown in FIG. 1.

FIG. 4 is a top view of a glass ribbon.

DETAILED DESCRIPTION

In the following detailed description, for purposes of explanation andnot limitation, example embodiments disclosing specific details are setforth to provide a thorough understanding of various principles of thepresent invention. However, it will be apparent to one having ordinaryskill in the art, having had the benefit of the present disclosure, thatthe present invention may be practiced in other embodiments that departfrom the specific details disclosed herein. Moreover, descriptions ofwell-known devices, methods and materials may be omitted so as not toobscure the description of various principles of the present invention.Finally, wherever applicable, like reference numerals refer to likeelements.

Ranges can be expressed herein as from “about” one particular value,and/or to “about” another particular value. When such a range isexpressed, another embodiment includes from the one particular valueand/or to the other particular value. Similarly, when values areexpressed as approximations, by use of the antecedent “about,” it willbe understood that the particular value forms another embodiment. Itwill be further understood that the endpoints of each of the ranges aresignificant both in relation to the other endpoint, and independently ofthe other endpoint.

Directional terms as used herein—for example up, down, right, left,front, back, top, bottom—are made only with reference to the figures asdrawn and are not intended to imply absolute orientation.

Unless otherwise expressly stated, it is in no way intended that anymethod set forth herein be construed as requiring that its steps beperformed in a specific order. Accordingly, where a method claim doesnot actually recite an order to be followed by its steps or it is nototherwise specifically stated in the claims or descriptions that thesteps are to be limited to a specific order, it is no way intended thatan order be inferred, in any respect. This holds for any possiblenon-express basis for interpretation, including: matters of logic withrespect to arrangement of steps or operational flow; plain meaningderived from grammatical organization or punctuation; the number or typeof embodiments described in the specification.

As used herein, the singular forms “a,” “an” and “the” include pluralreferents unless the context clearly dictates otherwise. Thus, forexample, reference to a “component” includes aspects having two or moresuch components, unless the context clearly indicates otherwise.

An apparatus for winding glass ribbon together with interleavingmaterial into a roll will now be described. The apparatus includes aninterleaving material supply path, a glass ribbon supply path, a rollwinding mechanism, and a means for applying tension to interleavingmaterial traveling along the interleaving material supply path, as theinterleaving material is wound into the roll, so as to produce pressurebetween the layers of the roll. By applying a suitable tension to theinterleaving material, there is developed a suitable pressure betweenthe layers of glass ribbon and interleaving material in the roll wherebya roll with straight sidewalls can be produced. Additionally, the meansfor applying tension may be coupled to a roll that supplies theinterleaving material, or to the interleaving material as it travelsalong its supply path, either directly or through a roller or rollersystem. A suitable controller may be coupled to the means for applyingtension so as to control the means for applying tension in accordancewith input received from sensors measuring either one or both of theamount of interleaving material on the interleaving-material-supply rollor the amount of material wound into the roll of glass ribbon andinterleaving material.

One embodiment of an apparatus for winding glass ribbon together withinterleaving material into a roll will now be described in connectionwith FIGS. 1-3.

FIG. 1 is a schematic drawing of an apparatus for rolling a glass ribbon10 together with interleaving material 20. The apparatus includesrollers 18 for guiding the glass ribbon 10, and rollers 30 for guidingthe interleaving material 20. The rollers 18 and 30 respectively guidethe glass ribbon 10 and the interleaving material 20 along respectivesupply paths toward a position where they may be wound together into aroll 40.

As shown in FIGS. 1-2, the roll 40 may include a core 42, having acentral longitudinal axis 43 about which the core 42 rotates in thedirection of arrow 44. A cross section of the roll 40 is shown in FIG.2, which is a view taken along line 2-2 in FIG. 1, but which omits thetop layer of interleaving material so as to make illustration moreclear. As seen in FIG. 2, the roll 40 includes glass ribbon 10,interleaving material 20, and optionally a core 42 around which theglass ribbon 10 and interleaving material 20 are wound in alternatelayers. In the roll 40, each the glass ribbon 10, and the interleavingmaterial 20, is shown as being disposed in three layers, however, theremay be any suitable number of layers of each in the roll.

Returning to FIG. 1, a sensor 48 is disposed so as to measure the amountof glass ribbon 10 and interleaving material 20 disposed on roll 40;this may be done by measuring the diameter or radius of the material onthe roll 40. For example, sensor 48 may be an ultrasonic, laser, orcontact, sensor. A roll winding mechanism 46 (see FIG. 3) is shownschematically as being coupled to the core 42 by arrow 47 so as torotate the core 42 about axis 43. The winding mechanism 46 may be amotor, for example, servo motor, stepper motor, or motor driving aclutch, and may be controlled by any suitable controller as known in theindustry.

The interleaving material 20 has a width 21 and is supplied in thedirection of arrow 25 from an interleaving-material supply roll 22. Theroll 22 has a central longitudinal axis 23, and rotates in the directionof arrow 24 as interleaving material 20 is pulled into roll 40. As shownin FIG. 3, a pneumatic brake 26 is coupled to the interleaving-materialsupply roll 22 so as to control the rotation thereof and, thus, applytension to the interleaving material 20 as it is wound into roll 40. Asuitable pneumatic brake is available from Nexen, headquartered inVadnais, MN. A sensor 28 is disposed so as to measure the amount ofinterleaving material 20 disposed on roll 22. Similarly to sensor 48,the sensor 28 may be an ultrasonic, laser, or contact, sensor forexample, which measures the diameter or radius of material on the roll22. As noted above, the interleaving material itself advantageously maybe chosen to reduce the effects of thickness variation in the glassribbon. More specifically, if the interleaving material 20 is thicknesscompliant, or has some give to it when compressed, it can absorbthickness differences that may be present in the glass ribbon 10. Asuitable stiffness for the interleaving material 20 was found to be lessthan or equal to about 28.14 N/mm, or less than or equal to about 27.12N/mm, or less than or equal to about 26.1 N/mm, wherein the lower boundfor all ranges was greater than zero. In order to achieve theabove-noted stiffness, the interleaving material 20 may be formed from,for example, a polyethylene foam (either open or closed cell), acorrugated paper material, or a sheet of soft polyvinyl material havingan embossed or textured surface.

A controller 50 is coupled to sensor 48 by path 52, and to sensor 28 bypath 54. Further, the controller is coupled to a control valve 60 bypath 56. The controller 50 may be, for example, a programmable logiccontroller, or a general or special purpose computer. A suitableprogrammable logic controller is available from Allan Bradley, adivision of Rockwell Automation headquartered in Milwaukee, Wis. If thecontroller 50 is a general or special purpose computer, it may also becoupled to the winding mechanism 46 to control that device. The paths52, 54, and 56, may be wires for conducting electrical signals, or maybe conduits for conducting fluids (for example, pneumatic or hydraulic).The control valve 60 may be a pneumatic or electrically controlledproportional valve, for example. A suitable control valve is availablefrom SMC, headquartered in Noblesville, Ind.

The control valve 60 is coupled to a fluid source by path 62, and topneumatic brake 26 by path 64. The control valve 60 receives fluid at aconstant pressure along path 62, and allows fluid at a variable amountof pressure out along path 64 in response to a signal received alongpath 56 from the controller 50.

Methods of forming a roll of glass ribbon and interleaving material,whereby the roll has straight side walls, are also described. Themethods include controlling the tension in terms both of amount, and howit is, applied to the materials being wound. More specifically, arelatively low amount of tension (greater than zero and ≦0.25 pounds perlinear inch width (≦0.3 kg/cm)) is applied as the materials are beingwound, and that tension is applied to the interleaving material; not tothe glass ribbon. By controlling the amount and manner in which tensionare applied to the materials being wound, a suitable pressure betweenthe layers in the roll can be developed, whereby there are attainedstraight side walls in the roll.

One embodiment of a method for forming a roll of glass ribbon andinterleaving material, wherein the roll has straight side walls, willnow be described in connection with FIGS. 1-4.

The glass ribbon 10 is fed from an upstream process, for example,directly from a forming process—for example, a down draw, slot draw,fusion draw, up draw, or float, process—or from any type of conveyanceprocess, including a process of conveying the glass ribbon during usethereof. In any case, the glass ribbon 10 is fed from the upstreamprocess along direction 15 toward roll 40, which rotates in a direction44. Before reaching the roll 40, the glass ribbon 10 enters a free loop19 formed between guide rollers 18. The free loop 19 separates theupstream process from the rolling process, i.e., it compensates fordifferences in glass-ribbon-travel speed between the upstream androlling processes. At about the same time that glass ribbon 10 is fedtoward roll 40, an interleaving material 20 is unwound from roll 22rotating in direction 24 and is fed along direction 25. The interleavingmaterial 20 is positioned relative to the roll 40 by guide rollers 30.According to one aspect, the interleaving material 20 is wound aroundcore 42 (see FIG. 2) one or more times before glass ribbon 10 is fedinto a nip 45 between successive layers of interleaving material 20.According to another aspect, the glass ribbon 10 may be wound around thecore 42 first and then the interleaving material 20 fed into a nipbetween successive layers of glass ribbon 10. In either case, the glassribbon 10 and interleaving material 20 are wound together in alternatinglayers to form a roll 40 around core 42. The core 42 may remain in theroll 40 or be removed therefrom. When the core 42 is to remain in theroll 40, the inner-most layer (either interleaving material or glassribbon) may be attached to the core 42. Keeping the core 42 in the roll40, and attaching the interleaving material 20 to the core 42 assists inpreventing the entire wound glass/interleaving material pack from sideshifting during unwinding in subsequent processes steps.

FIG. 4 is a top view of a glass ribbon 10 which, as noted above, may beproduced by any suitable method, for example, down-draw, fusion draw,up-draw, slot draw, or float. The glass ribbon 10 has a thickness 4 (seeFIG. 2), which may be from about 50 microns to about 300 microns, andedges 3 a, 3 b which may be as-formed edges (including beads as shown inFIG. 2) or cut edges (not shown, but having the beads removed). Theribbon-forming process can produce variations in the thickness of theribbon across its width, as well as “camber” in the motion of theribbon. FIG. 4 illustrates a glass ribbon 10 which exhibits camber 5(greatly exaggerated in this figure for purposes of illustration). Ascan be seen, camber 5 is a continuous curvature of the ribbon in onedirection (i.e., to the left in FIG. 4). Such curvature can be causedby, for example, different rates of cooling of a ribbon's edge beads.Camber, thickness variation, and residual stresses in the glass ribboncan cause the ribbon to shift laterally, rather than conveying in astraight line. And upon attempting to wind the glass ribbon into a roll,this lateral shift causes the sides of the roll to be “dished”,“telescoped”, or otherwise not straight, i.e., straight side walls wouldgenerally include each of the edges 3 a, 3 b located substantially inone plane.

In order to overcome the effects of camber and/or thickness variation,the winding parameters for making roll 40 are chosen as set forth below.The winding parameters include how tension is applied to the materialsbeing wound, the amount of that tension, and the resulting pressurebetween layers in the roll. The parameters may be useful separately fromone another, or in any and all combinations, based on differentcircumstances.

First, tension is applied to the interleaving material 20; not to theglass ribbon 10. Because of the camber and/or thickness variation in theglass ribbon 10, the inventors have found that attempting to place anysignificant amount of tension on the glass ribbon 10 as it is woundcauses the side walls of the roll 40 to be “dished”, “telescoped”, orotherwise not straight. Accordingly, the only tension applied to theglass ribbon 10 as it is being wound is that resulting from its ownweight in the free loop 19. On the other hand, however, the inventorshave found it desirable to apply tension to the interleaving material20, as the interleaving material 20 is wound together with the glassribbon 10, in order to produce a roll 40 with substantially straightside walls.

The tension applied to interleaving material 20 is established by thepneumatic brake 26 which is coupled to the roll 22 and thus provides aforce resisting the pull on the interleaving material 20 by roll 40 asit winds the interleaving material 20 together with the glass ribbon 10.Accordingly, the tension can be applied to the interleaving material 20by controlling the pneumatic brake 26. In the embodiment shown, thepneumatic brake 26 is controlled by the controller 50 via the controlvalve 60. For example, in a pneumatic system, the control valve 60 is aproportional control valve that is coupled to a source of air atconstant pressure by path 62. The control valve 60 also receives aninput signal from controller 50 via path 56. The signal from controller50 may be based either on an input from sensor 28 or an input fromsensor 48. The control valve 60 then outputs air at a decreased pressurealong path 64, wherein the amount of pressure decrease is based on thesignal input from controller 50. When controller 50 uses the result of ameasurement from sensor 48 to produce the output signal to control valve60, the control valve 60 decreases pressure along path 64 according toincreasing roll 40 diameter. On the other hand, when controller 50 usesthe result of a measurement from sensor 28 to produce the output signalto control valve 60, the control valve 60 decreases pressure along path64 according to decreasing roll 22 diameter. In either case, thepressure along path 64 decreases. In response to the decreasing pressureon path 64, the pneumatic brake 26 applies a decreasing baking force onroll 22. Accordingly, the tension in interleaving material 20 can bedecreased as a function of either increasing roll 40 diameter, ordecreasing roll 22 diameter, which is beneficial for the reasons notedabove, including maintaining a suitable pressure between the layers ofthe roll 40.

The signal from sensor 28 may also be used to adjust the amount oftension established by the pneumatic brake 64 at the start of a windingoperation after a roll 22 of interleaving material 20 is firstly loaded.For example, a roll 22 may not always be full when first loaded in thewinding apparatus. Accordingly, the tension established by the pneumaticbrake 64 may be adjusted (by the controller 50) to a value appropriatefor the size of the roll 22 by making a measurement of the size of theroll 22 with sensor 28 after the roll 22 is loaded but before a windingoperation with that roll 22 starts. By knowing the size of the roll 22,an appropriate amount of breaking may be selected by the controller 50to produce the desired amount of tension in the interleaving material 20as it is unwound. Similarly, the signal from sensor 48 may be used toadjust the amount of tension at the start of winding a roll 40. That is,when the sensor 48 detects a roll 40 diameter indicative of a new roll40, the controller 50 can adjust the force applied by the pneumaticbrake 26 so as to develop a tension suitable for the start of the roll40. Again, as noted above, as the material on the roll 40 thenincreases, a decreasing amount of tension may be applied to interleavingmaterial 20.

Second, the amount of tension applied to the interleaving material 20 ischosen to be ≦0.25 pounds per linear inch (≦0.3 kg/cm) of width 21 ofthe interleaving material 20. More specifically, the inventors foundthat typical web winding process parameters of 1-2 pounds per linearinch of web tension (0.18 to 0.36 kg/cm), and 15-50 pounds per squareinch of pressure (0.1-0.35 MPa) between the layers, when used with athin glass ribbon 10 and interleaving material 20, produced angled sidewalls in the roll. Further, contrary to conventional wisdom, theinventors found that increasing the web tension and pressure between thelayers actually made the side wall characteristics worse. Surprisingly,the inventors found that using lower web tension (and applying thattension to the interleaving material 20) and lower pressure between thelayers (of glass ribbon 10 and interleaving material 20) producedstraighter side walls in the roll 40. More particularly, a tension ofgreater than 0 pounds per linear inch, but 0.25 pounds per linear inchor less (0.3 kg/cm), applied to the interleaving material 20, producedstraight side walls on the roll 40.

As noted above, it is advantageous to decrease the amount of tensionapplied to interleaving material 20 as the roll 40 increases in size, soas to—among other things—maintain a suitable pressure between the layersin the roll 40. Because the above-noted tension range is given in forceper unit width, the total amount of tension is directly dependent of thewidth 21 of the interleaving material 20. That is, the total amount oftension simply is the tension in pounds per inch multiplied by theinches in the width 21 of the interleaving material 20. On the otherhand, the tension applied to the interleaving material 20 is largelyindependent of the speed at which roll 40 rotates.

Third, the pressure between the layers of glass ribbon 10 andinterleaving material 20 in the roll 40, as a result of theabove-described winding conditions, also plays a part in producing aroll 40 with straight side walls. By controlling the above-describedwinding conditions, the resultant pressure between the layers in theroll 40 can be maintained greater than zero and ≦10 pounds per squareinch (≦0.07 MPa). According to another aspect, the pressure between thelayers in the roll 40 can be maintained greater than zero and ≦7 poundsper square inch (≦0.05 MPa). As noted above, maintaining a pressurebetween the layers (glass ribbon 10 and interleaving material 20) of theroll 40 within the noted ranges, advantageously a roll 40 havingstraight sidewalls can be produced. Further, it is desirable to maintaina substantially constant inter-layer pressure through the roll 40.

EXAMPLE 1

A glass ribbon having a thickness of 150 microns was wound into a rolltogether with an interleaving material of irradiated cross linkedEthylene Vinyl Acetate (EVA) copolymer foam having a thickness of 1/32inch, a width of 11 inches (28 mm), and a density of 6 lbs. per cubicfoot (0.1 grams per cubic cm) (available from FLEXcon of Spencer, Mass.as FLEXcon P.E.F. 32 white no PS). The roll was started by winding theinterleaving material around a roll core (having a nominal diameter of20 inches (508 mm), 18 inch (457 mm) minimum diameter, and 24 inch (610mm) maximum diameter), and then feeding glass ribbon to a nip formed bythe interleaving material. The parameters for winding the roll were asfollows:

-   -   the roll was wound at a speed of 12.5 to 28 feet per minute (    -   the diameter of the finished roll (as measured to the outermost        layer of the glass ribbon and interleaving material) was less        than 29 inches    -   the breaking torque applied to the interleaving material roll        was 5 in-lbs (0.56 Nm) at the start of rolling, and was        decreased to 1 in-lb (0.11 Nm) at the end of rolling.    -   the diameter of the interleaving roll material ranged from 22        inches (559 mm) (1050 ft. (320 m) on the roll) to 18.5 inches        (470 mm) (700 ft. (213 m) on the roll)    -   the tension applied to the interleaving material was        approximately 0.06 to 0.12 pounds per linear inch (0.011 to        0.022 kg/cm)    -   the resulting pressure between layers in the roll was measured        to be less than 7 pounds per square inch (0.05 MPa)—the lower        detection limit of the pressure indicating sensor film (by        FujiFilm, Japan, distributed through Sensor Products Inc.)        placed between a layer of glass ribbon and a layer of        interleaving material    -   controller 50 was Allen Bradley, model RS Logix 500, by Rockwell        Automation, Milwaukee, Wis., USA    -   pneumatic brake 22 was a Nexen model 800113    -   control valve 60 was an SMC electronic regulator        Using the above parameters and equipment, a roll of glass ribbon        and interleaving material was wound, wherein the roll had        straight sidewalls.

EXAMPLE 2

A glass ribbon and interleaving material were wound together into a rollin the same manner, and with the same equipment, as set forth in Example1, except that the pneumatic brake was set at 5.5 in-lbs (0.62 Nm) oftorque, 12 psi (0.084 MPa), for the entire rolling process, whereby itapplied a tension of approximately 0.07 pounds per linear inch (0.013kg/cm) to the interleaving at the start of rolling, which tensionlinearly increased to 0.5 pounds per linear inch (0.09 kg/cm) by the endof rolling. The roll of glass ribbon and interleaving material did nothave straight sidewalls.

It should be emphasized that the above-described embodiments of thepresent invention, particularly any “preferred” embodiments, are merelypossible examples of implementations, merely set forth for a clearunderstanding of various principles of the invention. Many variationsand modifications may be made to the above-described embodiments of theinvention without departing substantially from the spirit and variousprinciples of the invention. All such modifications and variations areintended to be included herein within the scope of this disclosure andthe present invention and protected by the following claims.

For example, although the core 42 is shown without flanges on its ends,flanges could be present. Further, the flanges could be permanentlyattached to the core 42, or could be removable.

Additionally, although three layers of interleaving 20 and three layersof glass ribbon 10 are shown as being wound on a roll 40, any suitablenumber of layers of either may be present.

Further, although a pneumatic example was given for purposes ofillustration, other methods and devices can be used. For example,instead of using a pneumatic brake, a servo motor run in torque modecould be used and controlled by varying the input current. When using aservo motor, the proportional control valve would not be pneumatic, andmay be omitted if suitable control can be performed by controller 50, aswhen controller 50 is a general or special purpose computer. Stillfurther, the pneumatic brake could be replaced by any other suitabletype of tension applying device, for example, a mechanical frictionbrake, a magnetic particle brake, an electric brake, or a servo motor.Any one of these devices, that applies tension to the interleavingmaterial, traveling along the interleaving material supply path as theinterleaving material is wound into the roll 40, so as to producepressure between the layers of the roll, acts as a means for applyingtension to the interleaving material.

Moreover, although the pneumatic brake is shown as being coupled to theroll of interleaving material directly, instead either the pneumaticbrake, servo motor, or other tension applying device, could be coupledto the interleaving material by a separate roller or roller system. Sucha roller system could be integrated with the guide rollers 30 thatdirect the interleaving material 20 along the supply path in thedirection of arrow 25. The interleaving web could also be wrapped arounda roller with load cells incorporated into the bearing mounts. Theseload cells could be calibrated to measure tension in the interleavingdirectly, and this information could then be used by the control systemto maintain the appropriate tension, as described above. Oneconsideration is that the means for applying tension apply tension tothe interleaving material, as it is being wound together with the glassribbon, so as to produce a pressure between the layers of interleavingmaterial and glass ribbon. By maintaining a suitable inter-layerpressure in the roll, there is produced a roll having straight sidewalls.

1-17. (canceled)
 18. A method of manufacturing a glass article,comprising: forming a glass ribbon; and winding an interleaving materialand the glass ribbon together; controlling the interlayer pressureduring winding so as to produce a roll having a substantially constantinter-layer roll pressure between the interleaving material and theglass ribbon, wherein the roll inter-layer pressure is controlled bytensioning the interleaving material, and further wherein the tensioningis controlled so as to decrease tension as a function of increasing rolldiameter.
 19. (canceled)
 20. An apparatus for winding glass ribbontogether with interleaving material into a roll, comprising: aninterleaving material supply path; a glass ribbon supply path; a rollwinding mechanism; and a means for applying tension to interleavingmaterial traveling along the interleaving material supply path, as theinterleaving material is wound into the roll, so as to produce apressure between the layers of the roll.
 21. The apparatus according toclaim 20, wherein the means for applying tension is one of a pneumaticbreak and a servo motor coupled to the interleaving material. 22-24(canceled)
 25. The apparatus according to claim 21, further comprising ameasurement device positioned to measure a diameter of a roll from whichthe interleaving material is supplied along the interleaving materialsupply path, and further comprising a controller coupled to themeasurement device and the means for applying tension, wherein thecontroller controls the means for applying tension so as to decrease thetension applied to the interleaving material as a function of decreasinginterleaving-roll diameter.
 26. The apparatus according to claim 20,wherein the means for applying tension applies an amount of tension ofgreater than zero and ≦0.25 pounds per linear inch.